Field of the Invention
This document relates to a liquid crystal display device.
Related Art
An active matrix driving type liquid crystal display displays video using a thin film transistor (TFT) as a switching element. Compared with cathode ray tubes (CRTs), the liquid crystal display may be reduced in size so as to be applied to televisions and display devices of portable information devices, office machines, computers, etc., rapidly replacing CRTs.
In a liquid crystal display, pixels are formed as data lines and gate lines intersect each other, and include thin film transistors (TFTs) connected to the intersections of the data lines and the gate lines. In response to a gate pulse from a gate line, each TFT supplies a data voltage supplied through a data line to a pixel electrode of a liquid crystal cell. Driven by an electric field generated according to a voltage difference between a voltage of a pixel electrode and a common voltage Vcom applied to a common electrode, the liquid crystal cell adjusts an amount of light passing through a polarizing plate. A storage capacitor is connected to the pixel electrode of the liquid crystal cell to maintain a voltage of the liquid crystal cell.
The common voltage Vcom applied to the common electrode may cause a ripple phenomenon due to electrical coupling with the pixel electrode. The ripple phenomenon of the common voltage Vcom is proportional to variations of a data voltage over time. Thus, in an inversion scheme driven by varying the polarity of the data voltage, a variation of the data voltage is so large that the ripple phenomenon of the common voltage Vcom becomes severe the moment a polarity of the data voltage is changed. The ripple phenomenon of the common voltage Vcom causes a line dim phenomenon in a horizontal direction, degrading display quality.